<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Document</title>
        <style>
            .a {
                width: 100px;
                height: 100px;
                border: 10px solid yellow;
                background: orange;
            }

            .b {
                width: 120px;
                height: 120px;
                padding: 50px;
                background: red;
                border: 20px solid black;
            }

        </style>
    </head>
    <body>
        <div class="b">
            <div class="a"></div>
        </div>
        
    </body>
</html>